The need for keyed right-angle locks for doors and windows is well established. The size of such locks must be kept small to fit the dimensions of mounting surfaces. These constraints determine to a great degree the applicable mechanism.
The use of rack and pinion gears to change rotary motion to linear motion, and vice versa, is well known. The use of two such systems to produce reciprocating motion at right angles is also well known and has been described for example in U.S. Pat. Nos. 1,195,881; 1,251,467; 2,431,105; 3,561,805; and 4,163,375. Except for U.S. Pat. No. 4,163,375, the patent disclosures are not suitable for patio door locks, due primarily to their bulk.
In U.S. Pat. No. 4,163,375, two rack and pinion systems, mounted at right angles to one another are used to extend and to retract the bolt. And although a rack and pinion system is ideally suited to provide reciprocating motion of a cylindrical bolt in order to provide a bolt that is free to rotate to inhibit sawing in a forced entry attempt, such a system is unnecessarily complex for the barrel lock assembly drive mechanism. Thus, there exists a need for a small, sturdy, key-operated right-angle lock that provides for maximum security, is easily made, and can be used in essentially every conceivable position while at the same time concealing the means for holding the lock assembly together, and in which the bolt can be locked when extended in either direction, and the barrel lock easily replaced, when necessary or desirable.